Coil Balance?

Hello! I recommend our 15-192 pivot shoe, Series 170 coil spring, 15-156 cover, and 15-157 cover drum. The video below will show you how all these parts fit together.

To clarify, you don't really want 'the strongest' balance when it comes to window balances, and coil balances in particular. You want one that is calibrated specifically to handle your window sash's weight. Nor are the different types of balances 'better' than any other; it all comes to what fits your window. In this case, as Tom said, the 15-192 with the Series 170 Coil Balances is what you need.

Now, you do need to choose a spring weight for your Series 170 balances. This spring weight designates, again, the amount of weight your coil springs are designed to support. Look for stamp codes on the springs that indicate this. If there are none or you are uncertain, obtain the exact weight of your window sash. Give us that exact weight and we can work out what you need.